Is there a reason why you don't just want to pay 10 pounds, and get a SIM card with 5 pounds credit good for one year?

I would think some of the shops at Heathrow would sell them.

Yonatan

Edited to add: it looks like there's a virgin store in T1 which I assume would sell their 'starter pack' (=SIM card).

[This message has been edited by yonatan (edited Mar 10, 2004).]